Traditionally, flywheels have been made of metals such as steel. Due to the high density and moderate specific strength of many metals, this material may not be optimal for flywheel construction. In addition, metal flywheels tend to fail in large, sharp fragments at high speeds. Accordingly, composite materials such as fiber reinforced resin matrix composites have been used to produce flywheels since composite materials have a higher specific strength than metals.
Even though composites may be more advantageous to use in flywheel construction than metals, composite flywheels can still fail at high speeds. Composite flywheels tend to fail by fracturing into flywheel debris such as dust and long strands of fiber.
If the flywheel fails, containment of the dust and fiber strands is necessary to prevent damage to the flywheel and surrounding structures. Conventionally, layers of heavy metals, such as steel and lead, surround the flywheel to absorb the force of the flywheel debris. Although the metal layers prevent sharp edged strands from piercing the containment device, they often fracture. In addition, the metal layers are incapable of capturing the dust. If the dust is not captured, it may flow into areas of a vacuum chamber surrounding the flywheel resulting in the need for full encompassing containment. The metal layers of conventional containment devices are also incapable of dissipating a significant amount of energy into material strain rather than heat.
Additionally, conventional containment devices can be costly and heavy. Consequently, the application of conventional containment devices can be severely limited. For example, conventional containment devices can limit the use of a flywheel energy storage system in mobile environments, such as vehicles.
Accordingly, there exists a need for a light weight, flywheel containment device that captures dust and dissipates a significant amount of energy into material strain rather than heat if the flywheel fails.
Disclosure of the Invention
The present invention relates to a light weight, flywheel containment device that captures dust and dissipates a significant amount of energy into material strain rather than heat if the flywheel fails.
An aspect of the invention includes a shaft, defining an axis of rotation, and a flywheel having an annular shaped cross-section perpendicular to the axis of rotation. The flywheel is connected to the shaft and has an outer diameter and an inner diameter. The containment device also comprises an annular shaped honeycomb structure with an annular shaped honeycomb layer having an outer diameter and an inner diameter greater than the outer diameter of the flywheel. The honeycomb layer comprises a plurality of pores that are open on the inner diameter of the honeycomb layer to trap dust created if the flywheel fails. The honeycomb layer is positioned around the outer diameter of the flywheel such that the honeycomb structure is independent from the flywheel. The device also includes means for supporting the honeycomb structure. A containment vessel is also positioned around the outer diameter of the honeycomb structure.